Bag closure



March 1, 1966 'H. HUGHES 3,237,844

BAG CLOSURE Filed Sept. 28, 1964 2 Q l 22;???) 22 62 3 d 3 12 .l%laey 1%;9955

A TTOR/VEYS United States Patent 3,237,844 BAG CLOSURE Harry Hughes, Norton-on-Tees, England, assignor to linperial Chemical Industries Limited, London, England, a corporation of Great Britain Filed Sept. 28, 1964, Ser. No. 399,667 Claims priority, application Great Britain, Oct. 7, 1963, 39,402/63 Claims. (Cl. 22953) This invention relates to vented bags, and more particularly relates to bags having vents that permit the escape of air without readily permitting either the escape of the contents of the bags or the ingress of air or of contaminants such as for example water.

The term bag as used in this specification is intended to cover bags of all shapes and sizes, and embraces both fiat and gusseted bags. In particular it includes large bags which are often described as sacks: indeed the invention may be applied with especial advantage to bags of such type. The term is also intended to include unsupported bags and liners for bags, and in the latter case the outer bags may be made of different material from that of the inner bags or liners.

Bags to which the invention may be applied are useful for the packaging of for example granular solids and small articles. More specifically, the invention may advantageously be applied to bags for storing granular fertilizers.

According to the invention a bag made of flexible material is provided with a vent comprising an interrupted seam between opposed faces of the bag closing otf a minor portion from the bag interior with one or more interruptions; a second seam between the said faces of the bag on the side of the interrupted seam remote from the bag interior, the opposed faces of the bag being flattened together between said seams; and a communication to the exterior from within the flattened region between said seams, spaced from any interruption in said interrupted seam.

By the provision of the vent in accordance with the invention, air or other gas, or liquid, contained in the bag is permitted to escape through the spaces in the interrupted seam and thence through the communication to the exterior, and the flattened walls between the seams act as a valve against the ingress of air.

The interrupted seam may have only one interruption, but preferably comprises two or, particularly, several interruptions. An interruption may be at any position along the length of the interrupted seam, including at the end thereof. Thus for example the invention covers the case where the interrupted seam is a continuous but incomplete seam having a gap at each end between the end of the seam and the side, or another seam, of the bag. The said communication to the exterior of the bag may conveniently consist of one or more holes in the material of the bag enclosing the space between the interrupted and continuous seams; this space may also be partly defined by an edge fold of the bag. These holes may be made either before the bag is filled or after, when it is desired to remove the air, or other gas or liquid from the filled bag.

The bag may be designed for a particular use so that the spaces in the interrupted seam are insufiiciently large readily to permit the passage therethrough of the material or articles that the bag is intended to contain.

A vent according to the invention may be applied to a bag which has already been filled; or it may be applied to an empty or partly filled bag which is capable of being filled, either through a filling valve or through an opening in the bag which may be sealed after the bag has been filled.

The invention also provides a method of packaging material or articles in a bag made of flexible material. In this method, the material or articles may first be filled into the bag and the vent provided by forming the interrupted seam and the second seam across at least a part of the filling opening, the closure of the bag being completed if and as required. Alternatively, the vent may first be provided and the bag then filled, either through a filling valve or, more generally, through an opening in the bag which is seamed after the bag has been filled. It will be appreciated that, although the interrupted and continuous seams are referred to as the first and second seams, they may be formed simultaneously, or either may be formed before the other.

The vent may be formed across the whole or part of one end opening of the bag, or, for example, may be formed diagonally across a corner. If desired, there may be more than one vent applied to a bag. For example a bag may be provided with vents at both corners of one end of the bag. In a particularly preferred form of the bag of the invention, the bag is an open mouthed bag pro vided with a vent across each corner of the closed end, and preferably with an incompleted vent at each corner of the open end (to be completed on closing the filled bag) in a manner that will be described hereinafter.

Various forms of the bags and method of the invention will now be more particularly described, by way of example, with reference to the accompanying drawings, of which:

FIGURE 1 shows two opposite end corners of a particularly preferred form of the bag;

FIGURES 2 and 3 are transverse sections through corners at the closed end of the bag after filling, close to the bot-tom seam of the bag; and

FIGURES 4 and 5 show other forms of the bag of the invention.

In FIGURE 1: 1 represents the body of a 36 inch x 20 inch open mouthed bag, which is suitably formed of 0.008 inch thick polythene film; 2 is the bottom seam of the bag; 3 is a diagonal interrupted seam between the opposed walls of the bag, one such seam being provided across each bottom corner of the bag, the seams suitably being heat seals inch wide with spaces, 4 of inch being left in the centre of each seam, and between the ends of the seams and the bottom seam and side folds of the bag; and 5 is a 0.04 inch diameter hole through both the bag walls. The spacing of the seal 3 from the corner is suitably such that the line of the inner side of the seal intersects the side fold and bottom seam of the bag at from 2% to 3 /2 inches from the corner, and the hole 5 is preferably from 1% to 1% inch from the interrupted seam. At the open end of the bag, 7 represents the line along which the bag will be seamed after filling; 8 is an interrupted seam across the corner, having the form of a cranked mitre so that a straight sided mouth, 9, is provided for the bag; 10 are spaces in the seam or between the seam and the side fold of the bag; and 11 is a hole through both the bag walls. The dimensions and arrangement of the seam, 8, spaces 10, and holes 11, are such that the top corners of the bag after closing are essentially similar to the bottom corners, except that the edges of film projecting beyond the top seam, suitably about 1 inch wide, are wider than those projecting beyond the bottom seam. It will be seen that the end portions of the seam 2 and of the seam formed at 7 constitute said second seam in accordance with the invention.

FIGURES 2 and 3 illustrate an unforeseen and important advantage of the bags provided with corner vents of the type shown in FIGURE 1. This is that the corners, 12, of the bag when the bag has been filled assume a position as shown in either FIGURE 2 or FIGURE 3; this means that water drains oh? the vent holes, and that the vent holes are lifted clear of any surface water, when the sacks are laid flat. This is a great advantage, since an important feature of the usefulness of plastics sacks, particularly for the packaging of fertilizers, is that they may be stored out of doors if they are constructed in a water-tight manner. The provision of a straight sided mouth in the open bag reduces the risk of tearing the bag at the interrupted seams during filling.

In FIGURE 4 is shown a bag, suitably of similar size and of similar material to that of FIGURE 1, in which: an interrupted seam, 13, is provided across one end of the bag by heat sealing, the seam containing a number of spaces, 14; a continuous seam, 15, is provided beyond the interrupted seam; and in the flattened area separating the seams a number of holes 16, pass through both thicknesses of film. The spaces 14 in the interrupted seam may be, for example, about 12 in number and 0.375 inch wide; the separation between the seams 13 and 15 may be about 0.5 inch; and the holes 16 may be about 12 in number, preferably in staggered relationship to the spaces in the interrupted seam, and of about 0.01 inch diameter. The seams are preferably formed to provide the closed end of an open mouthed bag, the mouth of which may be closed by a seam, 17, after filling.

FIGURE shows a similar type of bag, but the vent is formed diagonally across a corner instead of across one end. In this figure: 18 represents the interrupted seam, with spaces 19; 20 is the continuous seam; 21 are the holes in the flattened portion between the two seams; and 22 is the seam across the end of the bag, which may be continued to the corner if more convenient. The corner of the bag beyond the continuous seam 20 may be cut off if desired. Here again, this end of the bag is preferably the closed end of an open mouthed bag, which is closed at 23 after filling. The bag of FIGURE 5 possesses the advantage shown by the bag of FIGURE 1 and demonstrated in FIGURES 2 and 3, this advantage being obtained particularly when the holes 21 are Well spaced from the interrupted seam 18.

Any air trapped in the bags of the invention during sealing can readily be expelled through the small holes merely by pressing the bags to flatten them, and the flattened areas beyond the interrupted seams act as valves against the ingress of air after its expulsion.

It will be appreciated that many modifications may be made in the bags particularly described. For example, bags of the type shown in FIGURE 1 may if preferred be provided with a plain open mouth and sealed across after filling to form a normal pillow end. In general, where corner vents are provided, they may be at one or more corners of the bag, but are preferably at both corners of either end, and it is especially preferred to form them at all four corners, to provide symmetry when the bag has been filled and closed. Alternatively, any corners not provided with a vent as described may be mitred by a simple seam to match the vented corners in shape. Advantages of the corner mitres, with or without vents, are that they enable sharp corners in the filled bags to be avoided, these corners tending to damage adjacent bags when the filled bags are stacked; and the rounded corners i protect the bottom of the bag if it is dragged over surfaces or similarly mistreated.

The holes in the flattened area between the seams, providing the communication to the exterior of the bag, may be in only one thickness of the plastics or other flexible material, but for ease of manufacture of the bags will be generally through both thicknesses as described. There may be only one space in, or at an end of, the interrupted seam; but there are preferably two or more spaces, so that air may be more readily expelled from the filled bag.

If desired more than one interrupted seam may be formed, in order to decrease any tendency for the contents of the bag to escape through the spaces. For example two substantially parallel seams with staggered spaces may be provided.

The invention is particularly useful for bags made of sheet plastics material, such as for instance polythene or polyvinyl chloride film, as such material is substantially impervious to air. The bag may conveniently be made from a length of lay flat tubing.

The seams may be formed in a variety of ways, such as by use of adhesives, by sewing, or by heat sealing, the latter being preferred for the seaming of plastics material. When the material of the bag is polythene film the seals are preferably formed by the application of heat and pressure; and when the material is polyvinyl chloride high frequency heating is a particularly useful method of forming the seals.

When sheet plastics material is used and the interrupted seam has spaces along its length, it is preferred to form this seam by means of a conventional sealing machine adapted to provide an interrupted seam, for example by the use of a heated, notched blade which presses the plastics material on to a rubber roller, the latter being provided with a non-stick surface in relation to the material being used. High frequency welding machines may be similarly modified by the provision of a notched blade. Alternatively the interrupted seam may be formed, for example, by inserting a thin comb of non-stick material, such as for instance a material coated with polytetrafluoroethylene, or a non-stick foil, for example of vinyl chloride/vinyl acetate copolymer, between the film surfaces and sealing the film in the interstices by using a continuous sealing blade to apply heat and pressure.

I claim:

1. In a plastic bag of the type that is closed at its ends by heat sealing, the improvement comprising a vent means in at least one corner of said plastic bag, said vent means comprising an aperture through the corner of at least one wall of said bag for venting the interior of said bag to the atmosphere, a seam between the walls of the bag and in a position between the aperture and the remainder of said bag, said seam following a diagonal path, said path intersecting an end seam of said bag and a side fold of said bag so as to close oif a minor portion of the bag interior in the region of said aperture, and at least one opening through said seam for providing a communication between the interior of the minor portion of said bag and the remainder of said bag interior.

2. The improvement of claim 1 wherein said seam is an interrupted seam, whereby the interruption in the seam forms the communication between said bag interior and said vent.

3. A bag as claimed in claim 1 having a diagonal seam between the walls of the bag and across each of the four corners of the bag at least one of said seams being associated with a vent means in a corner of the bag, and being provided with at least one of said openings through said seam.

4. A bag as claimed in claim 3 in which one end of the bag is open, the closed end is provided at each corner with a vent means associated with a diagonal seam which is provided with at least one opening through said seam,

5 and the open end of said bag is provided at each corner with a diagonal seam between the Walls of the bag, said last named seam being cranked to provide at the bag mouth an end portion of the seam that is parallel to the sides of the bag.

5. A bag as claimed in claim 4 in which each of said seams at the open end contains at least one opening in its diagonal portion and is associated with an aperture through the Wall of the bag in the corner of the bag, said aperture serving to provide a vent means when the bag has been closed by seaming it across its mouth.

References Cited by the Examiner UNITED STATES PATENTS Yates 22962 Snyder 206--56 X Stannard 22953 Carnerini 229-53 Corbett 22953 Olsson 229-62 10 JOSEPH R. LECLAIR, Primary Examiner.

D. M. BOCKENEK, Assistant Examiner. 

1. IN A PLASTIC BAG OF THE TYPE THAT IS CLOSED AT ITS ENDS BY HEAT SEALING, THE IMPROVEMENT COMPRISING A VENT MEANS IN AT LEAST ONE CORNER OF SAID PLASTIC BAG, SAID VENT MEANS COMPRISING AN APERTURE THROUGH THE CORNER OF AT LEAST ONE WALL OF SAID BAG FOR VENTING THE INTERIOR OF THE BAG AND THE ATMOSPHERE, A SEAM BETWEEN THE WALLS OF THE BAG AND IN A POSITION BETWEEN THE APERTURE AND THE REMAINDER OF SAID BAG, SAID SEAM FOLLOWING A DIAGONAL PATH, SAID PATH INTERSECTING IN END SEAM OF SAID BAG AND A SIDE FOLD OF SAID BAG SO AS TO CLOSE OFF A MINOR PORTION OF THE BAG INTERIOR IN THE REGION OF SAID APERTURE, AND AT LEAST ONE OPENING THROUGH SAID SEAM FOR PROVIDING A COMMUNICATION BETWEEN THE INTERIOR OF THE MINOR PORTION OF SAID BAG AND THE REMAINDER OF SAID BAG INTERIOR. 